{"id":37337,"date":"2015-02-24T10:20:12","date_gmt":"2015-02-24T10:20:12","guid":{"rendered":"http:\/\/www.massarate.ma\/?p=37337"},"modified":"2015-02-24T10:20:12","modified_gmt":"2015-02-24T10:20:12","slug":"did-dark-matter-kill-the-dinosaurs","status":"publish","type":"post","link":"https:\/\/www.massarate.ma\/did-dark-matter-kill-the-dinosaurs.html","title":{"rendered":"Did dark matter kill the dinosaurs?"},"content":{"rendered":"

$\"Did$ <\/p>\n

Some of Earth\u2019s past mass extinctions have been caused by the impacts of extraterrestrial objects, such as the asteroid that struck near Mexico\u2019s Yucat\u00e1n Peninsula and wiped out the dinosaurs about 66 million years ago. Others have occurred during extended periods of geological disruption that include region-smothering volcanic eruptions. Both kinds of catastrophes seem to occur on a cycle of about 30 million years, notes Michael Rampino, a geoscientist at New York University in New York City. \u201cIt\u2019s always been a mystery as to how extraterrestrial impacts could cause these long-lived geological effects,\u201d he says. But invisible dark matter, he proposes, could trigger both extraterrestrial impacts and geological upheavals in one fell swoop.<\/p>\n

Scientists still don\u2019t know what dark matter is, but its gravitational pull on other objects in space shows that there\u2019s a lot of it out there. Researchers estimate that in the plane of the galaxy, each square light-year contains about one solar mass of dark matter. Like the clouds of dust and gas that astronomers can see, clouds of dark matter may be perturbing the orbits of distant comets, causing them to fall into the inner solar system where they can strike Earth.<\/p>\n

But those clouds could directly affect Earth as well, Rampino says. As the solar system passes through this purported haze of particles clogging the galactic plane, some get trapped by Earth\u2019s gravity, Rampino suggests. These particles orbit Earth\u2019s core and eventually fall to the center of the planet, where they interact with normal matter or one another, releasing energy that gets transformed into heat.<\/p>\n

In the time it takes for the solar system to cross the galactic plane, interactions with dark matter could raise the temperature of Earth\u2019s core by hundreds of degrees Celsius<\/a>, Rampino reported online this week in the Monthly Notices of the Royal Astronomical Society<\/em>. Then, over millions of years, that heat could be carried to Earth\u2019s surface via massive plumes of hot buoyant rock that, in turn, create volcanic hot spots or slowly rip apart continents\u2014possibly altering global climate or making huge swaths of the planet so inhospitable that millions of species perish.<\/p>\n

The idea that dark matter might cause both extraterrestrial impacts and geological upheavals \u201cis intriguing,\u201d says Dennis Kent, a geophysicist at the Lamont-Doherty Earth Observatory in Palisades, New York. \u201cOne of those sources of environmental disruption might be tolerable,\u201d he notes, but together they might pack a one-two punch that is too much for many ecosystems to bear. Indeed, he adds, some rather large impacts that weren\u2019t accompanied by widespread geological devastation\u2014such as an object that slammed into what is now the Chesapeake Bay nearly 35 million years ago, leaving a now-buried crater\u2014don\u2019t seem to have caused significant ecological damage.<\/p>\n

sciencemag<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"